The second best known synth company in the early 70ies. Alan R.Pearlman founded the Tonus Inc in the US and later changed to ARP. they where the big ones beside Moog until the polyphonic synths came. the Odyssey and ARP2600 were a good addition to the Moogs and sounded less "typical moog". After the hard struggle making a guitar synth (the avatar sold about 300 times) they changed to a very innovative new synth, the Chroma but closed their doors in the early/mid 80ies and sold it to CBS (which was sold to Rhodes/Fender).